Stretching bridge for metal sheets of rotary printing machines



Dec. 28, 1937. 1 E EmcKE 2,103,617

STRETCHiNG BRIDGE FOR METAL SHEETS OF ROTARY PRINTING MACHINES Filed Jan. 12, 1937 ATTORNEY.

Patented Dec. 28,1937

UNITED STATES PATENT 1 OFFICE g s'rns'rcnme names Fon METAL snnn'rs or sonar rnm'rmdmcnmss Erich Gericke, Berlin-Pankow, Germany, as-

signor to the firm Rotaprint Akt.-Ges., Berlin,

- Germany 9 Claims.

In the known stretching devices for metal sheets in printing machines the metalsheets are fixed on the printing cylinders'eitlier by means of screws or by means of stretching bars subjected to spring action. The devices mentioned in second instance present the advantage over those mentioned in first instance that they can be more'conveniently and more quickly operated. The first mentioned devices, that is those with screw fixation, are also known with additional covering members which are likewise attached vices it is unavoidable to first remove the bridge,

then to clamp the sheet and then replace the bridge. As all the parts are secured by screws a considerable amount of time must be expended in this work. i

The invention relates to a stretching device which is as easy to manipulate as the devices with clamping bar= subjected to spring action and which also has a bridge covering, the clamping gap in the cylinder. This bridge, which is intended to protect against injuring is, however, not an additional member and is not screwed on to the cylinder as heretofore known but consists of parts of the stretching device and is actuated therewith in one and the same operation.

An embodiment of the invention is illustrated, 'by way of example, in the accompanying drawing in which:-

Fig. 1. shows in perspective view a printing cylinder with metal sheet stretched thereon.

Fig. 2 is a similar view to Fig. 1 showing the fixing of the sheet on the cylinder.

In the drawing a printing cylinder is shown such as is employed in a rotary printing machine. Its periphery is formed by a member 3 and by parts 9, I, i, 6, 2, 8 and 4 which extend like a bridge from the left hooks 12 to the right hooks II. The shell like parts I and 2 are shown broken away at their front ends to enable the spring 5 to be seen. 9 is a fixed stretching bar with hooks l2 and 4 a stretching bar oscillatable about an axle Ill and also provided with hooks l2 between which the metal sheet I3 is clamped in that the hooks engage in holes I4 in the metal sheet. The above mentioned bridge is formed by the parts I and 2 which are hingedly connected by a hinge rod 6. The part I is also oscillatable on the rigid stretching bar 9, by means of the axle rod 1 and the part 2 is likewise hingedly connected with the movable stretching bar 4 by means of an axle rod 8. The stretching bar 4 is itself 'pivotable about screws Ill. The parts 9, l, I, 6, 2, 8, 4 and III are therefore arranged in a hinge system with four hinge points and form a changeable curve gear with fixed pivot points 1 and I0. All the parts are held in the position shown in Fig. 1 by springs 5. If, the parts being in the position shown in Fig. 1, pressure is exerted on the part 2 or on the part I, part 4 will swing outwards into the position shown in Fig. 2. The distance along the periphery of the cylinder between the hooks l2 for the metal sheet becomes smaller, the metal sheet I! can be slipped on to the hooks l2 by means 0! the holes l4 as shown in Fig. 2. If this pressure ceases the parts return into their initial positions under the action covered by the bridge and accidents are avoided.

This bridge may be restricted to a smaller portion or extended to a larger portion of the circumference of the cylinder than that shown in the drawing, in which thebridge occupies about one third of the periphery of the cylinder.

The bridge therefore consists of parts of the stretching device and forms part ofthe stretching device. The stretching bars 9 and 4 are shown in the illustration with hooks l2 which engage in holes l4 in the metal sheet i3. Clamping or other holding means may also be employed for the metal sheet instead of these hooks.

I claimz- A device for stretching printing sheets on printing cylinders and covering the stretching gap in the cylinder, comprising in combination with a cylinder body forming a part of the periphery of the cylinder and having a stretching gap, 2. stretching bar fixed on said body on one side of said gap, a second stretching bar articulated on said body on the other side of said gap, and parts hingedly connected toboth of said bars and at the same time bridging the gap.

2. A device for stretching printing sheets on printing cylinders and covering the stretching gap in the cylinder, comprising in combination with a cylinder body forming a part of the periphery of the cylinder and having: a stretching s i a gap, and parts hingedly connected to both of said gap, 9. second stretching bar articulated on said body on the other side of said gap, and parts hingedly connected to both of said bars and at the same time bridging the gap, and shaped in accordance to the shape of the periphery of said body.

3. A device for stretching printing sheets on printing cylinders and covering the stretching gap in the cylinder, comprising in combination with a cylinder body forming a part of the periphery of the cylinder and having a stretching gap, a stretching bar fixed on said body onone side of said gap, a second stretching bar articulated on said body on the other side of said said bars and at the same time bridging the gap, and shaped in accordance to the shape of the periphery of said body, said parts forming at the same time link levers of a link system.

4. A device for stretchingprinting sheets on printing cylinders and covering the stretching gap in the cylinder, comprising in combination with a cylinder body forming a part of the periphery of the cylinder and having a stretching gap, a stretching bar fixed on said body on one side of said gap, a second stretching bar articulated on said body on the other side, of said gap, and parts hingedly connected to both of said bars and at the same time bridging the gap, and shaped in accordance to the shape of the periphery of said body, and a spring adapted to maintain said parts in their bridging position.

5. A device for stretching printing sheets on printing cylinders and covering the stretching gap in the cylinder, comprising in combination with a cylinder body'iorming a part of the periphery oi the cylinder and having a stretching gap, a stretching bar fixed on said body on one side of said gap, a second stretching bar articulated on said body on the other side of said gap, and parts hingedly connected to both of said bars and at the same time bridging the gap, and shaped in accordance to the shape of the periphery of said body, said parts forming at the same time link levers of a link system and adapted to displace under pressure to shift said movable stretching bar.

6. A device for stretching printing sheets on printing cylinders and covering the stretching stretching bar fixed on said body on one side of gap in the cylinder, comprising in combination with a cylinder body forming a part ofthe pee.

riphery of the cylinder and having a stretching gap, a stretching bar fixed on said body on one side of said gap, a second stretching bar articulated on said body on the other side of said gap, and parts hingedly connected to both oi said bars and at the same time bridging the gap, and shaped in accordance to the shape of the periphery of said body, said parts forming at the same time link levers of a link system and adapted to displace under pressure to shift said movable stretching bar, means on said bars for holding the edges of a printing sheet, and a spring adapted to maintain said parts in their bridging position and at the same time stretch said metal sheet over said cylinder body.

7. A device for stretching printing sheets on printing cylinders and covering the stretching gap in the cylinder, comprising in combination with a cylinder body forming a part of the periphery of the cylinder and having a stretching gap, a stretching bar fixed on said body on one side of said gap, a second stretching bar articulated on said body on the other side of said gap, and parts hingedly connected to both of said bars and at the same time bridging the gap, and shaped in accordance to the shape of the periphery of said body, said parts forming with said bars and said cylinder body a link system with four hinged points.

8. A device for stretching printing sheets on printing cylinders and covering the stretching gap in the cylinder, comprising in combination with a cylinder body having a stretching gap, two sets of sheet engagement means arranged at the sides of said gap in variable peripheral distance and an arched bridge of variable length bridging said gap, and controlling said peripheral distance, said bridge consisting of two parts pivotally connected with each other and with the cylinder and being adapted to be collapsed inwardly and lengthened by exterior pressure and to be shortened by spring action.

9. A device as in claim 8 in which by the same spring action the bridge parts are held in bridging position and the two sets of sheet engagement means in stretching position.

ERICH GERICKE. 

